CN111332030A

CN111332030A - On-board ink-jet printer

Info

Publication number: CN111332030A
Application number: CN201911319906.9A
Authority: CN
Inventors: 斯特凡诺·斯佩扎尼
Original assignee: Keraglass Industries Srl
Current assignee: Keraglass Industries Srl
Priority date: 2018-12-19
Filing date: 2019-12-19
Publication date: 2020-06-26
Anticipated expiration: 2039-12-19
Also published as: US11090947B2; SMT202300475T1; PT3670199T; US20200198376A1; IT201800020215A1; PL3670199T3; EP3670199A1; CN111332030B; BR102019027355A2; EP3670199B1; ES2968896T3

Abstract

An ink jet printer (10) on a board (L) comprising: a support (20) for supporting the plate (L); a locking and centering assembly (40) configured to contact the plate (L) to temporarily lock and center the plate (L) on the support (20); and a printing device (30) provided with at least one inkjet print head (31), the at least one inkjet print head (31) being movable relative to the support (20) along a sliding direction (D) and spaced apart from the support (20), wherein the inkjet print head (31) is configured to release the decoration on a surface (L1) of a board (L) resting on the support (20).

Description

On-board ink-jet printer

Technical Field

The present invention relates to ink jet printers on rigid plates, such as digital ink jet printers, in particular, but not for the purpose of limitation, transparent plates, such as glass plates, or plates of any type, such as ceramic plates, natural stone plates, metal plates, etc.

Background

As is known, an ink jet printer for printing on a plate has: a conveyor on which a plate with an upwardly facing surface to be decorated rests; and a printing module equipped with one or more printing heads (printing heads) suitable to be arranged above the plate to release a number of drops of ink or decorations on the surface to be decorated of the plate itself.

In the field of ink-jet printing on plates (e.g. rigid plates), two substantially different types of printers are known.

A first known type of printing machine provides for: travelling on a conveyor in steps along the direction of travel and sliding the printing module at each step in a direction perpendicular to the direction of travel (forwards and backwards) to release a strip of decoration covering the entire width of the board to be decorated on a limited axial section of the surface of the board to be decorated. The progressive advance of the plate, with the printing module sliding transversely with respect to the plate, makes it possible to progressively decorate the entire length of the plate with a succession of decorations.

A second known type of printing machine (also referred to as single-pass printing machine) provides for: the board travels on a conveyor at a substantially constant speed in the direction of travel, and the printing modules are fixed above the conveyor, for example on a cross beam that engages the entire span of the conveyor, to remain fixed.

A drawback encountered in both types of printing machines described above is that the decorations printed by them are not particularly precise. Such defects are more pronounced when decorating transparent sheets, for example glass sheets, whose transparency makes the printing defects more pronounced, which may be mainly due to slight movements and/or sliding of the sheets on the conveyor during the same sheet travel, for example between one travel step of the sheets and the next (in a first type of printing machine) or a successive travel (in a second type of printing machine).

In addition, another drawback encountered in so-called single-pass presses is that it is practically impossible to perform two inking "passes" which can be substantially parallel, thus affecting the printing quality.

The object of the present invention is to overcome the aforementioned drawbacks of the prior art with a simple, rational and low-cost solution.

In particular, it is an object of the invention to provide an ink jet printer which makes it possible to manufacture particularly clear and precise decorations without defects that can be perceived by the naked eye even when the plate is a transparent plate.

Furthermore, it is an object of the invention to avoid that the board is contaminated or dyed and that the surface opposite to the decorated surface is contaminated or dyed.

These objects are achieved by the features of the invention given in the independent claims. The dependent claims outline preferred and/or particularly advantageous aspects of the invention.

Disclosure of Invention

In particular, the present invention provides an ink jet printer for printing on a panel, comprising:

a support for supporting the plate;

a locking and centering assembly configured to contact the plate to temporarily lock and center the plate on the support; and

a printing device provided with at least one inkjet print head movable in a (mutual) sliding direction relative to a support (e.g. on the support) and arranged spaced apart from the support, wherein the inkjet print head is configured to release a decoration on a surface of a board resting on the support.

Thanks to this solution, the plate is firmly held on the support during printing by the printing head, and therefore decoration is particularly accurate and precise in high definition even for transparent plates, where such decoration is visible under light and requires high quality standards.

Furthermore, the entire surface of the board can be decorated effectively with a single pass (e.g. in a single pass machine), or if multiple passes are required, the pass after the first pass is perfectly centered and calibrated with respect to the previous pass.

According to an advantageous aspect of the invention, the support may comprise a horizontal resting plane comprising a travel assembly for the travel of the supported plate (resting, preferably directly, on the resting plane) along a predetermined horizontal travel direction (i.e. parallel to the resting plane).

Advantageously, the travelling assembly may comprise (or consist of) a motorized conveyor (such as a single-belt conveyor or a multi-belt conveyor or a roller conveyor), for example a motorized roller conveyor, the rollers of which define integrally the rest plane.

Thanks to this solution, the possibility of soiling the surface of the board opposite to the surface to be decorated with printing ink is reduced or minimized, which is particularly useful when using transparent panels, wherein possible soiling in the surface opposite to the surface to be decorated will remain visible when using the panel.

Furthermore, since the locking and centering assembly also serves to protect the resting plane (i.e. of the rollers) from the drops released by the printing device, it also allows and/or maximizes such an aspect due to the presence of the locking and centering assembly (and its construction which will be described better below).

Even more advantageously, the roller may be a ceramic roller, i.e. a roller whose outer shell consists of only ceramic shells.

Thanks to this solution, the roller can be made inert to thermal radiation and other wear stresses, thus prolonging the service life of the support, which is undoubtedly advantageous in terms of the operability of the printing machine.

According to one aspect of the invention, the locking and centering assembly comprises at least one pair of rods mutually movable on the support and configured to releasably laterally grip a plate arranged to rest on the support.

Thanks to this solution, the plate is particularly stable and fixed, without interfering with the surface to be decorated, when the decoration is deposited.

Furthermore, thanks to the configuration of the locking and centering assembly, it is possible to perform an effective locking and centering of slabs of various specifications in a cost-effective and easily adaptable manner.

According to another aspect of the invention, the locking and centring assembly comprises at least one front flap adapted to stop the plate (L) from travelling in the direction of travel.

Thanks to this solution, it is possible to effectively stop the travel of the plate on the resting plane and at the same time define a fixed reference system for the plate itself on the resting plane.

A further aspect of the invention provides that the printing device may comprise a set of print heads positioned side by side, the set of print heads being offset and/or aligned in a side by side direction and being mutually movable as a whole.

Preferably, the dimension of the set of print heads in the side by side direction may be at least equal to or greater than the edge of the sheet L to be decorated.

Thanks to this solution, by a single pass, decorations can be deposited that can occupy the entire (upper) surface of the plate.

According to a first embodiment, the sliding direction of the print head of the printing device on the support may be horizontal and parallel to the travelling direction.

According to an alternative second embodiment, the sliding direction of the print head of the printing device on the support may be a horizontal and vertical travel direction.

Advantageously, the printing device may comprise a heating device movable on the support in the sliding direction as a whole with the print head and spaced apart from the support.

Thanks to this solution, it is possible to preheat the surface to be decorated of the panel and/or to dry the decorations deposited on the decorated surface of the panel.

Advantageously, the heating device may be aligned with the print head in an alignment direction parallel to the sliding direction and arranged upstream or downstream of the print head in the direction in which the print head slides in the sliding direction.

Furthermore, the heating device may comprise or consist of an infrared lamp.

According to another advantageous aspect, the printing machine may comprise a measuring assembly configured to measure at least one dimension of the plate, for example the width and/or the length of the plate itself.

Thanks to this solution, it is possible to provide (before printing) a measurement of the actual dimensions of the board to be decorated (i.e. the actual printing area) and therefore calibrate the printing device, so that it can print precisely in such a printing area, optimizing the decoration and reducing the waste of ink.

Advantageously, the measuring assembly can be arranged on the locking and centering assembly or arranged to cooperate with the locking and centering assembly in any case.

For the same purpose outlined above, another aspect of the present invention provides an inkjet printing method on a board, the inkjet printing method comprising the steps of: supporting the plate on a support; temporarily locking the plate on the support by bringing the plate into contact with a locking and centering assembly movable on the support; and releasing the decoration on the surface of the plate by moving an inkjet print head of the printing device located on the plate resting relative to (and above) the support and spaced apart from the support.

Drawings

Other features and advantages of the invention will become more apparent from reading the following description, which is provided by way of example and not for limitative purposes, with the aid of the attached drawings listed below.

Fig. 1 is an isometric view of a system for decorating panels equipped with a printing press according to the invention.

Fig. 2 is an isometric view of a printing press according to a first embodiment of the present invention, with the buffer housing removed for a better understanding of the drawing.

Fig. 3 is an isometric view of a printer according to a second embodiment of the invention, with the buffer housing removed for a better understanding of the drawing.

Fig. 4 is an isometric view of a roller conveyor (equipped with centering and locking assemblies) of a printing press according to the invention, according to both a first embodiment and a second embodiment.

Fig. 5 is a first axonometric view of the centring and locking assembly of the printing machine according to the invention, according to both the first and the second embodiments.

Fig. 6 is a second axonometric view of the centring and locking assembly of the printing machine according to the invention, according to both the first and the second embodiments.

Fig. 7 is a side view of fig. 2.

Fig. 8 is a plan view of fig. 2 in a first operating step of the printer.

Fig. 9 is a plan view of fig. 2 in a second operating step of the printer.

Fig. 10 is a plan view of fig. 2 in a third operating step of the printer.

Fig. 11 is a side view of fig. 3.

Fig. 12 is a plan view of fig. 3 in a first operating step of the printer.

Fig. 13 is a plan view of fig. 3 in a second operating step of the printer.

Fig. 14 is a plan view of fig. 3 in a third operating step of the printer.

Description of the reference numerals

Plate L horizontal support wall 362

Surface L1 longitudinal guide 363

Linear motor 37 of printer 10

Heating device 38 of support 20

Rest plane a locking and centering assembly 40

Traveling direction B rod 41

Roller conveyor 21 supports cross beam 410

Roller 210 support column 411

Motor 211 first drive unit 42

Frame 212 first linear actuator 421

First rotating electric machine 423 of printing apparatus 30

Second rotary motor 422 of print head 31

Front baffle 43 in parallel direction C

Second linear actuator 44 supporting the overhead vehicle 35

Lower wall 350 cushioning shell 50

Side plate 351 electronic control unit U

Sled 352 preheater 60

Drying device 70 with sliding direction D

Support structure 36

Vertical supporting wall 361

Detailed Description

With particular reference to these figures, a system for decorating rigid plates is described, in particular but not for the purpose of limitation, optically transparent plates, such as glass plates, generally indicated with the letter L.

The term "slab" L is intended to mean any sheet of any material, for example, preferably glass and ceramic, but also metal, natural stone or other material suitable for the manufacture of slabs.

Furthermore, the plate L may have any shape or size, for example, it may be flat or concave, polygonal or circular or a combination thereof.

The system includes an inkjet printer 10, preferably a digital inkjet printer, the inkjet printer 10 being configured to release an ornament on a surface L1 of one or more boards L.

The printing machine 10 comprises a support 20 for supporting at least one board L resting with its lower supporting surface opposite an upper surface L1 to be decorated.

The support 20 comprises a horizontal resting plane a on which the panels L are intended to rest with their surface to be decorated L1 facing upwards.

Preferably, the support 20 comprises a travel assembly for causing the plate L, supported on (resting on, preferably directly on) the resting plane, to travel along a predetermined horizontal travel direction B (substantially rectilinear).

In the preferred example shown, the travelling assembly comprises a roller conveyor, in particular a roller conveyor 21, the roller conveyor 21 generally providing a plurality of rotating rollers 210 arranged parallel to each other and coplanar to each other to define the aforesaid horizontal resting plane a on which the board L to be decorated rests.

In practice, each roller 210 of the roller conveyor 21 rotates about its own horizontal axis and is perpendicular to the direction of travel B.

The rollers 210 of the roller conveyor 21 are connected to a motor 211 (see fig. 4), in particular by means of a conveying member, such as a chain or belt, to the motor 211, which is adapted to rotate the rollers 210 themselves in a synchronized manner so as to cause the plate L to travel along the aforementioned horizontal travel direction B (along one or both travel directions).

The rotational speed of the rollers 210 adjusts the travel speed of the plate L in the direction of travel B, which can be set and adjusted according to the machining requirements.

The roller conveyor 21 is equipped with a frame 212 for resting on the ground, in particular, the roller conveyor 21 is equipped with two side plates, the lower ends of which rest on the ground and the tops of which rotatably support the opposite distal ends of the rollers 210.

The motor 211 for driving the roller 210 may be arranged below the roller itself between the two side plates or in another suitable position.

The rollers 210 of the roller conveyor 21 are preferably ceramic rollers, i.e. rollers made (only) of ceramic material without any rubber coating.

Preferably, the rollers 210 of the roller conveyor 21 have a shell, for example substantially impermeable (e.g. glazed) or almost impermeable to water, which is rigid (i.e. does not deform during operation due to the loads to which it is normally subjected), preferably made of ceramic material (preferably, but not for limiting purposes, refractory material).

The main dimension of the roller conveyor 21 may be parallel to the direction of travel B set by the rollers 210.

Alternatively, the travel assembly may be defined by a conveyor belt, rack conveyor (carriage conveyor) or other conveyor of the type known in the printing press art.

The printing press 10 includes a printing device 30, and the printing device 30 is configured to release a predetermined ornament on a surface L1 (upper surface) of the board L.

The printing device 30 is preferably a digital (inkjet) printing device, as will be better described hereinafter.

The term "decorative" refers to the application of decorative fluids (e.g., pigmented and/or decorative inks) in general, as well as the application of any product in fluid, liquid, or semi-solid form, such as functional, coating, protective, or anti-reflective layers, and the like.

The printing device 30 comprises at least one inkjet print head 31, the inkjet print head 31 being equipped with ejector nozzles (not shown) adapted for a decorative fluid (e.g. ink, enamel, etc.) to be dispensed onto the surface L1 of the board L resting on the resting plane a provided by the roller conveyor 21.

The printing device 30 comprises a plurality of print heads 31, for example, placed side by side in a side by side direction C.

In the example shown, the printing device 30 comprises a plurality of parallel rows (in their example 2) of printing heads 31, each row of printing heads 31 being constituted by a plurality of printing heads 31 arranged side by side in a side by side direction C, for example offset from each other.

In general, the print head 31 or a set of print heads 31 has a main dimension (parallel to the side-by-side direction C of the print head 31, with more than one main dimension) at least equal to or greater than one of the sides (longer or shorter) of the sheet L to be decorated.

For example, the major dimension of the print head 31 or the major dimension of a component print head 31 is substantially equal to (or slightly less than) the length of the rollers 210 of the roller conveyor 21.

Each print head 31 is defined by a block, the lower surface of which engages the aforementioned ejector nozzle, which is therefore facing downwards, so as to be able to dispense drops of ink or other decorative fluid, when suitably driven by a suitable injector, on face L1 of the underlying plate L.

The print head 31 of the printing apparatus 30 may be of any known type without limitation.

The printing device 30 also comprises a feeding assembly (known per se) to feed the decorative fluid to each print head 31, which feeding assembly is in communication with one or more respective containers containing the decorative fluid itself.

Each feeding assembly comprises an electronic board which manages the operation of each print head 31 and therefore the individual ejector nozzles (by the respective ejectors).

The decorative fluid dispensed by each printhead 31 may be monochromatic or polychromatic, e.g., bi-chromatic.

The printing device 30 comprises a support trolley (35), which support trolley (35) is suspended on the resting plane a of the support (20), is at a non-zero distance from the resting plane a of the support (20), and moves itself parallel to the resting plane a with respect to the support (20).

The support empty carriage 35 comprises a generally box-shaped body.

For example, the support empty carriage 35 comprises a horizontal lower wall 350, which horizontal lower wall 350 is parallel to the resting plane a of the support 20 and is arranged at a predetermined distance from the resting plane a of the support 20 (for example, the height can be adjusted by means of suitable adjustment means, preferably by means of suitably motorized adjustment means).

The support empty carriage 35 (preferably the lower wall 350) comprises one or more housing seats (for example through openings) in which the respective print heads 31 (with their injector nozzles directed towards and kept at a predetermined distance from the rest plane a) are received.

The support trolley 35 further includes a pair of opposing side plates 351 rising from opposite sides of the lower wall 350, the pair of side plates 351 being parallel to each other and spaced apart along the side-by-side direction C to accommodate the entire major dimension of the print head 31 or the entire major dimension of a group of print heads 31 located therein.

The side plate 351 may be coupled with one or more bumper walls (e.g., at right angles to the side plate 351) to define a receiving space that supports the overhead vehicle 35, in which at least a portion of the feed assembly and/or supply tank of decorative fluid supplied to the printhead 31 may be received.

The support frame empty wagon 35 is slidably supported on the resting plane a.

In particular, the supporting trolley 35 is supported by the frame 212 of the roller conveyor 21 and is possibly slidable in a horizontal sliding direction D, i.e. parallel to (and spaced apart from) the resting plane a.

The sliding direction D is perpendicular to the side-by-side direction C of the print heads 31 supported by the support carriage empty carriage 35.

Preferably, the support structure 36 of the support frame empty wagon 35 is rigidly connected (i.e. firmly fixed) to the frame 212 of the roller conveyor 21 and is located above the resting plane a.

The support structure 36 includes a pair of

support walls

361, 362, the pair of

support walls

361, 362 being spaced apart by a distance equal to or greater than the major dimension of the support empty wagon 35 (i.e., its lower wall 350).

The supporting

walls

361 and 362 have longitudinal guides 363 rigidly fixed thereto, for example defined by channel beams with horizontal longitudinal axis, and to which suitable sliding runners 352 are connected and fixed to opposite side plates 351 of the support frame empty wagon 35.

Specifically, the support structure 36 includes a vertical support wall 361 and a horizontal support wall 362, and the vertical support wall 361 and the horizontal support wall 362 are individually supported by the frame 212 of the roller conveyor 21.

Correspondingly, a sliding slide 352 supporting the empty wagon 35, which is coupled with the longitudinal guide 363 of the vertical support wall 361, is laterally fixed to the outside of one of the side plates 351 of the support frame empty wagon 35, while the other sliding slide 352 of the support frame empty wagon 35, which is on the other side, is coupled with the longitudinal guide 363 of the horizontal support wall 362, is fixed below the opposite side plate 351 of the support frame empty wagon 35, for example under a shelf facing the outside of the respective side plate 351.

The support empty carriage 35 is driven by the linear actuator assembly to slide in both sliding directions along the sliding direction D.

Preferably, but not for limiting purposes, the drive assembly comprises a linear motor 37 (or consists of a linear motor 37), the linear motor 37 being supported by one of the supporting walls of the supporting structure 36, preferably by the vertical supporting wall 361.

The printing device 30 further comprises at least one heating device 38, the at least one heating device 38 being arranged close to the support 20, at a distance from the support 20, and being configured to heat the surface L1 of the board L resting on the resting surface a of the support 20.

The heating device 38 is preferably movable on the resting plane a of the support 20 and at a predetermined non-zero distance from the resting plane a of the support 20, fixedly connected to the print head 31 or to a group of print heads 31.

In practice, the heating device 38 is slidingly associated with the support 20 so as to be able to slide along the aforementioned sliding direction D together with the print head 31.

In the preferred embodiment, the heating device 38 is supported by the support trolley 35, such as adjacent a lower wall 350 of the support trolley 35.

The heating device 38 is, for example, an elongated body, the longitudinal axis of which is horizontal and parallel to the side-by-side direction C of the print head 31.

For example, the length of the heating device 38 is at least equal to or greater than one of the sides (longer or shorter) of the board L to be decorated, preferably substantially equal to (or slightly less than) the length of the rollers 210 of the roller conveyor 21.

The heating device 38 is in fact arranged with its longitudinal axis parallel to the side-by-side direction C of the print heads 31 and spaced apart from the side-by-side direction C of the print heads 31 (for example coplanar with respect to a horizontal plane), the heating device 38 being in fact aligned with the print head 31 or with a group of print heads 31 along an alignment direction parallel to the sliding direction D.

The heating device 38 may be arranged upstream and/or downstream of the print head 31 or a group of print heads 31 in respect of the sliding of the print head 31 (and the carriage trolley 35) in the sliding direction D.

In a preferred embodiment, the printing device 30 comprises a pair of heating devices 38, one heating device 38 being arranged upstream of the printing head or set of printing heads 31 and the other heating device 38 being arranged downstream of the printing head or set of printing heads 31, in the direction in which the printing head 31 (and the carriage trolley 35) slide along the sliding direction D.

The heating device 38 arranged upstream of the print head 31 serves as a preheating element adapted to preheat the surface L1 of the plate L before the print head 31 releases the decorative fluid onto the surface L1 of the plate L. The heating device 38 arranged downstream of the print head 31 serves as a drying element for the decorative fluid deposited by the print head 31.

Each heating device 38 comprises (or consists of) at least one infrared lamp or a plurality of infrared lamps.

In the first embodiment shown in fig. 1, 2, 4 to 10, the sliding direction D of the support trolley 35, i.e. the print head 31 (and each heating device 38), with respect to the support 20 is parallel to the travelling direction B imparted to the sheet L by the support itself, i.e. by the rollers 210 of the roller conveyor 21.

In this case, the supporting

walls

361 and 362 and therefore the longitudinal guides 363 supported by the supporting

walls

361 and 362 extend parallel to the direction of travel B, and preferably each of the supporting

walls

361 and 362 is supported above the respective side plate to rest on the assembly defining the frame 212 of the roller conveyor 21.

For example, the distance between the supporting wall 361 and the supporting wall 362 and thus the distance between the longitudinal guides 363 supported by the supporting wall 361 and the supporting wall 362 is substantially equal to the length of the rollers 210 of the roller conveyor 21.

Thus, the support trolley 35 is supported above the resting plane a defined by the rollers 210 of the roller conveyor 21, so that the side-by-side direction C of the print heads 31 is perpendicular to the travelling direction B.

The length of the longitudinal guide 363 (and/or of the supporting wall 361 or 362) is substantially equal to (or slightly less than) the length of the resting plane a along the direction of travel B.

In practice, the support empty carriage 35 can slide in the sliding direction D for a sliding stroke (maximum sliding stroke) substantially equal to the length of the resting plane a (defined by the rollers 210 of the roller conveyor 21) in the direction of travel B (which is greater than or equal to the maximum main dimension of the sheet L that can be decorated with the printing machine 10).

In this case, the main dimension of the print head 31 or set of print heads 31 is not smaller than the side of the sheet L that is perpendicular to the direction of travel B of the sheet L that can be decorated with the printer 10. In the second embodiment shown in fig. 1, 3, 4 to 6, 11 to 14, the sliding direction D of the support trolley 35, i.e. the print head 31 (and each heating device 38), with respect to the support 20 is perpendicular to the travelling direction B imparted to the sheet L by the support itself, i.e. by the rollers 210 of the roller conveyor 21.

In this case, the supporting

walls

361 and 362 and, consequently, the longitudinal guides 363 supported by the supporting

walls

361 and 362 extend perpendicularly to the direction of travel B, and preferably each of the supporting

walls

361 and 362 is supported on top of two side plates intended to rest on the ground defining the frame 212 of the roller conveyor 21, for example in a central region of the longitudinal direction of the resting plane a (i.e. of the roller conveyor 21).

For example, the distance between the supporting wall 361 and the supporting wall 362, and thus the distance between the longitudinal guides 363 supported by the supporting wall 361 and the supporting wall 362, is substantially equal to (or slightly smaller or slightly larger than) the length of the rollers 210 of the roller conveyor 21.

Thus, the support trolley 35 is supported above the resting plane a defined by the rollers 210 of the roller conveyor 21, so that the side-by-side direction C of the print heads 31 is parallel to the travelling direction B.

The length of the longitudinal guides 363 (and/or of the supporting walls 361 or 362) is substantially greater than the width of the resting plane a, i.e. greater than the length of the rollers 210 of the roller conveyor 21 (but, for example, less than the length of the resting plane a in the direction of travel B).

In practice, the support frame empty carriage 35 can slide in the sliding direction D by a (maximum) sliding travel substantially greater than the width of the resting plane a, i.e. greater than the length of the rollers 210 of the roller conveyor 21 (but, for example, less than the length of the resting plane a in the direction of travel B), for example greater than or equal to the edge of the sheet L that can be decorated with the printing machine 10, perpendicular to the direction of travel B of the sheet L.

In this case, the main direction of the print head 31 or the set of print heads 31 is not less than the side of the sheet L that is parallel to the direction of travel B of the sheet L that can be decorated with the printer 10.

In both illustrated embodiments, the printing press 10 comprises a locking and centering assembly 40, which locking and centering assembly 40 is configured to come into contact with the sheet L, temporarily lock the sheet L, i.e. hold or stop the movement imparted to the sheet L by the travelling assembly, and center the sheet L on the resting plane a defined by the support 20, for example in a predetermined zero position on the resting plane a.

The locking and centring assembly 40, shown in detail in figures 4 and 5, is configured to stop the movement (although it may be simultaneous) and to temporarily lock the travel of the sheet L (in the direction of travel B) on the resting plane a independently of the stop of the rotation of the rollers 210 of the roller conveyor 21.

In fact, the locking and centring assembly 40 is configured to stop the plate L and to temporarily lock it on the resting plane a, preventing the plate L from being able to move on the resting plane a even in accidental and unforeseeable situations, for the time required for the printing head 31 of the printing device 30 to deposit decorations on the surface L1 of the plate L itself.

In other words, the locking and centring assembly 40 is configured to define additionally (temporarily) the constraint of the plate L resting on the resting plane a with respect to the constraint defined by the resting plane itself.

Preferably, but not for limiting purposes, the locking and centering assembly 40 moves on the support 20, i.e. at least partially above the support 20.

In the example shown, the locking and centring assembly 40 comprises a pair of rods 41 mutually movable on the support 20 and configured to releasably laterally grip a plate L arranged to rest on the resting plane a of the support 20.

In practice, the bars 41 are movable with respect to each other in a movement direction perpendicular to the travel direction B imparted to the sheet L by the rollers 210 of the roller conveyor 21, hanging above (flush with) the resting plane a.

In a (preferred) embodiment, both levers 41 are movable towards and/or away from each other with respect to the resting plane a. However, this does not exclude the possibility that one of the two bars 41 may be fixed to the resting plane a and the other bar 41 is movable with respect to such fixed bar 41.

Each bar 41 is defined by an elongated (and thin) plate-like body having a horizontal longitudinal axis parallel to the direction of travel B of the plates L.

Each bar 41 comprises a vertical inner wall, i.e. facing the other bar 41, suitable for defining a contact surface with the (flat and vertical) plate L, i.e. with the opposite side wall of the plate L parallel to the direction of travel B.

The vertical inner wall can be covered, for example, with a gasket or (elastic) damping element, such as rubber or in any case with an elastic coating, to soften the mutual contact area between the stem 41 and the plate L.

The bars 41 are reciprocally movable between an extended position, in which the distance apart (i.e. the distance between the two vertical internal walls) is maximum and greater than the edge of the sheet L that can be decorated with the printer 10 perpendicular to the direction of travel B of the sheet L (for example, the distance apart is not less than the main dimension of the print head 31 or of a component print head 31), and a retracted position, in which the distance apart (i.e. the distance between the two vertical internal walls) is minimum and equal to the edge of the sheet L that can be decorated with the printer 10 perpendicular to the direction of travel B of the sheet L, i.e. the two bars 41 are in contact with the sheet L resting on the resting plane a.

In fact, when the rods 41 are in the deployed position, they allow the plate L to travel in the travel direction B on the resting plane a, since they do not interfere with the plate L, but when the rods 41 enter their retracted position (and the plate L is arranged between the rods 41), they stop the plate L from traveling in the travel direction B by interference, preventing any relative movement between the plate L and the resting plane a.

The distance of the bar 41 from the resting plane a of the sheet L is not less than the thickness of the sheet L that can be decorated with the printing machine 10.

For example, the distance of the bar 41 from the resting plane a can be adjusted according to the thickness of the plate L resting on the resting plane a.

For example, the distance of the bar 41 from the resting plane a is such that the bar 41 is in contact with a central zone of the thickness of the plate L.

For example, the distance of the bar 41 from the resting plane a is determined on the basis of the following formula:

d＝(S–s)/2；

where d is the distance between the bar 41 and the resting plane a, S is the thickness of the plate L and S is the thickness of the bar 41, where the thickness of the bar 41 is less than the thickness of the plate L.

Due to this configuration, in the case where the plate L has a chamfered edge (bevel) or a rounded edge or the like, the lever 41 can be brought into contact with a region of the side wall of the plate L which is not engaged by such processing, and the plate L can still be effectively held.

Each rod 41 may be comprised of a plurality of aligned segments or a single rod that are continuous and/or spaced apart from each other.

In this example, each bar 41 is supported above the resting plane a by a supporting cross-beam 410 arranged below the resting plane a, i.e. below (at a non-zero distance from) the rollers 210 of the roller conveyor 21. Each support beam 410 may be substantially parallel to the respective bar 41 with one or more support posts 411 upstanding from the bar 41, the base of the one or more support posts 411 being rigidly fixed to the support beam 410 and the bar 41 being rigidly fixed (e.g. in a removable manner) to the top of the one or more support posts 411.

Each support column 411 has a groove (with a gap) in the gap existing between two adjacent rollers 210 of the roller conveyor 21.

The locking and centering assembly 40 further comprises a first drive unit 42, the first drive unit 42 being configured to drive the rod 41 in a reciprocating motion alternately between the deployed position and the retracted position, as described above.

The first drive unit comprises a first linear drive 421 (e.g. a pneumatic drive), for example with a horizontal axis.

In this example, the first drive unit comprises at least one pair of first linear actuators 421, each linear actuator 421 being associated with a respective rod 41 for its (simultaneous) movement.

Alternatively or additionally, in order to centre or fine-tune the movement of the plate L between the deployed and retracted positions according to its width (in a direction perpendicular to its direction of travel B), the first drive unit 42 can be provided so as to be able to comprise a first motor (for example, a first rotary motor 423) adapted to move the respective rod 41 horizontally, or, as in the preferred embodiment, to move the (two) rods 41 horizontally.

Furthermore, the first drive unit 42 may be configured to perform an adjustment of the distance of the plate 41 from the resting plane a.

To this end, the first drive unit 42 may also comprise a second motor (e.g. a second rotary motor 422) adapted to move the respective rod 41 vertically, or, as in the preferred embodiment, to move the (two) rods 41 vertically.

The locking and centring assembly 40 can also comprise a front baffle 43, which front baffle 43 is adapted to be arranged on a resting plane a in front of the sheet L in a direction of travel of the sheet L in the direction of travel B (from entrance to exit), imparted by the rotation of the rollers 210 of the roller conveyor 21, to contact the front end of the sheet L and prevent the sheet L itself from traveling in the direction of travel B.

The front baffle 43 is adapted to come into contact with the front side wall of the sheet L resting on the resting plane a (in the direction of travel of the sheet L along the direction of travel B imparted by the rotation of the rollers 210 of the roller conveyor 21) to stop the sheet L on the resting plane a.

The front flap 43 is movable with respect to the support 20 (i.e. with respect to the resting plane a of the support 20) between a position of non-interference with the plate L, in which the front flap 43 is arranged in a position allowing the plate L to pass while travelling in the direction of travel, and a position of interference with the plate L, in which the front flap 43 is adapted to come into contact with the plate L to stop the movement of the plate L on the resting plane a.

In particular, the front baffle 43 is vertically, alternately slidably movable in a direction perpendicular to the resting plane a, i.e. between the aforesaid non-interference position and interference position.

In the example shown, in the interference position, the front shutter 43 is arranged above the resting plane a, for example at a distance from the resting plane a not greater than the thickness of the sheet L that can be decorated with the printing machine 10.

In the non-interference position, the front bezel 43 may be arranged (completely) below the resting plane a, for example retractable inside the interspace existing between two adjacent rollers 210 of the roller conveyor 21.

The front baffle 43 is defined by an elongated (and thin) plate-like body having a horizontal longitudinal axis perpendicular to the direction of travel B of the sheets L.

The front baffle 43 comprises a rear vertical wall, i.e. facing the plate L entering into the resting plane a in the direction of travel along the direction of travel B, suitable to define a (flat) contact surface with the plate L (i.e. with the front side wall of the plate L perpendicular to the direction of travel B), which is (vertical and) perpendicular to the direction of travel B.

In the example shown, the forward baffle 43 and the rod 41 intersect, for example close to the downstream end of the rod 41 (in the direction of travel of the plate in the direction of travel B), but this does not exclude the possibility of the forward baffle 43 being arranged at the downstream end or at the distal end of the rod 41 and axially spaced from the rod 41.

The rear vertical wall may be covered, for example, with a gasket or (elastic) damping element, such as rubber or in any case an elastic coating, to soften the area of mutual contact between the front baffle 43 and the plate L.

The locking and centring assembly 40 also comprises a second drive unit configured to drive the movement of the front shutter 43 with respect to the rest plane a alternately between the non-interference position and the interference position, as described above.

The second drive unit comprises a second linear drive 44 (e.g. a pneumatic drive), for example with a vertical axis.

According to an advantageous aspect of the invention, the printing machine 10 comprises a measuring assembly 45, the measuring assembly 45 being configured to measure at least one parameter indicative of a dimension (for example, a width and/or a length) of the sheet L arranged on the resting plane a (i.e. on the rollers 210 of the roller conveyor 21 of the printing machine 10).

In particular, the measuring assembly 45 is configured to measure the width (dimension parallel to the axis of rotation of the roller 210, i.e. dimension horizontal and perpendicular to the direction of travel B) and/or the precise length (dimension perpendicular to the axis of rotation of the roller 210, i.e. dimension horizontal and parallel to the direction of travel B) of the plate L.

The measuring assembly 45 comprises at least one sensor element configured to detect and determine the position of or the relative relationship between two (parallel) opposite vertical walls of the plate L, for example with respect to a reference system (x, y) on the resting plane a.

The measuring assembly 45 is defined as being integral with the locking and centering assembly 40 or on the locking and centering assembly 40.

In practice, the measuring assembly 45 is configured to determine the (mutual) position of two (parallel) opposite vertical walls of the plate L, i.e. the width and/or length of the plate L, as an indirect measure between two or more elements in the locking and centring assembly 40.

For example, in order to detect the width of the plates L, the sensor elements are configured to detect and measure the mutual distance between the rods 41 when the rods 41 are in their retracted position, i.e. they grip the plates L.

As stated, when the bars 41 are indeed in the retracted position, between which the plates L are arranged, the distance between the bars 41 is minimal and corresponds to the dimension of the width of the plates L, i.e. the dimension of the sides of the plates L perpendicular to the direction of travel B.

For this purpose, the sensor element may provide a position sensor 450 (as can be seen in fig. 5) (e.g. a tape position sensor), the position sensor 450 being fixed to one of the rods 41, e.g. fixedly connected with one of the rods 41 when the rods 41 are slid between the extended and retracted positions.

Preferably, each rod 41 leads (or is connected) to a respective position sensor 450.

The position sensors 450 are configured to determine the (absolute) position of the respective bars 41 (i.e. the respective inner vertical walls).

Each position sensor 450 is fixed, for example, below the resting plane a, for example rigidly fixed to (below) the supporting cross-beam 410 of the respective bar 41.

The sensor elements also comprise, for example, a magnetic tape 451, the magnetic tape 451 being, for example, longitudinal and having a longitudinal axis parallel to the rotation axis of the roller 210, i.e. horizontal and perpendicular to the direction of travel B, the magnetic tape 451 being fixed (i.e. stationary) with respect to the resting plane a, for example on a fixed beam at the frame 212 of the roller conveyor 21, below the resting plane a (below the roller 210).

Each position sensor 450 is (individually) configured to determine the position of the rod 41 from changes in the position of the rod 41 relative to (and along) the magnetic tape 451.

As an alternative to the above description, other measuring components may be provided, such as an optical component or a position sensor of a motor connected to the rod 41, such as an encoder or the like.

Further, in order to detect the length of the board L, the sensor element may be configured to detect and measure the distance between the front barrier 43 (when the vertical face of the front barrier 43 is in contact with the front side wall of the board L) and the (free) rear side wall of the same board.

To this end, the sensor element may provide a rear optical assembly (e.g. comprising a series of photocells or a camera or other means), not shown, which is for example fixed to the frame 212.

The rear optical assembly is configured to measure or determine the position of the (free) rear side wall of the (axially fixed) position (axially fixed) of the plate L with respect to the front baffle 43 in the direction of travel B (i.e. its front side wall of the vertical panel L is in contact) and thus determine the length of the plate L according to said measured or determined position.

The printing press 10 also includes a buffer housing 50 (visible only in fig. 1), the buffer housing 50 being closed to accommodate the support 20, the printing device 30 and the locking and centering assembly 40, and the buffer housing 50 being openable with suitable housing ports (hatches) to inspect the contents of the buffer housing 50.

Furthermore, the buffer housing 50 is equipped with at least one optically transparent window for detecting and checking the contents and the printing process performed by the printing press 10.

For example, the buffer housing 50 encloses an (internal) environment of the printing press 10, which may preferably be a controlled environment (e.g. climate controlled), wherein parameters of the air arranged inside are monitored and controlled.

Specifically, the printing press 10 includes a device adapted to control the climate inside the buffer housing 50 and a control assembly adapted to monitor and control parameters of the air inside the buffer housing 50 to optimize the printing operation.

The printing press 10 also comprises an electronic control unit U (only schematically shown in fig. 1) configured to manage the working steps of the printing press 10 in an automated manner.

The electronic control unit U is for example operatively connected to the motor 211 of the roller conveyor 21 and/or to the injector of the printing head 31 and/or to the linear motor 37 and/or to the first drive unit 42 (i.e. to the first linear drive 421, to the first rotary motor 423 and/or to the second rotary motor 422) and/or to the second linear drive 44, to manage and control the automatic operation of the printing machine 10.

The electronic control unit U may also be operatively connected to the measurement assembly 45.

In this case, the electronic control unit U may be configured to determine or measure at least one (actual) dimension of the board L (arranged in the printing machine 10) and to determine or change the decoration to be printed with the print head 31 (i.e. to change the drive of the print head 31) in accordance with the determined or measured dimension, in order to optimize the deposition of printing ink (only) on the surface L1 of the board L without exceeding the surface L1 of the board L.

With particular reference to fig. 1, in addition to what has been described above, the system may also include a preheating device 60, the preheating device 60 being configured to preheat (up to a predetermined temperature) the surface L1 of the sheet L before it is introduced into the printing press 10.

For example, the preheating device 60 is arranged upstream of the printing press 10 in the traveling direction of the sheet L in the traveling direction B imparted by the roller conveyor 21 of the printing press 10.

For example, the preheating device 60 (known per se to those skilled in the art) is equipped with a suitable inlet roller conveyor coplanar with the roller conveyor 21 of the printing press 10.

Furthermore, in addition to what has been described above, the system may also comprise a drying device 70, the drying device 70 being configured to heat the surface L1 of the sheet L (up to a predetermined temperature) and to dry the decorative fluid after it has been deposited by the printing press 10.

For example, the drying device 70 is arranged downstream of the printing press 10 in a traveling direction of the sheet L in the traveling direction B imparted by the roller conveyor 21 of the printing press 10.

The drying device 70, known per se to those skilled in the art, is for example equipped with a suitable exit roller conveyor coplanar with the roller conveyor 21 of the printing press 10.

In view of the above description, the operation of the printing press 10 (automatically managed and controlled by the electronic control unit U) is as follows.

The board L to be decorated travels on the conveyor line with its surface L1 to be decorated facing upwards (see fig. 1).

The board L, arranged and possibly preheated, enters the printing machine 10 (see fig. 7 to 8 and 11 to 12), i.e. it is received by a resting plane a, defined for example by the rollers 210 of the roller conveyor 21, and is advanced by the roller conveyor (or rollers) in a direction of travel B.

Preferably, when the sheet L enters the printing machine 10, the front shutter 43 is brought into its interference position (and the lever 41 is in its deployed position).

In this way, when the plate L reaches the front stop 43, the front stop 43 stops the travel of the plate L, which will stop at its predetermined axial zero position in the direction of travel B (see fig. 7 to 8 and 11 to 12).

At this point, the rod 41 (the non-interference position of which has been previously calibrated by the second rotary motor 422 and the distance from the resting plane a of which has been previously adjusted by the first rotary motor 423) is therefore driven (by the first linear actuator 421) from the extended position into the retracted position thereof (see fig. 9 and 13), in such a way that the plate L is firmly held and locked (stopped) with respect to the resting plane a.

Furthermore, the lever 41 in the retracted position locks the plate L in a direction perpendicular to the direction of travel B in a predetermined transverse zero position of the plate L, which preferably, but not for the sake of limitation, corresponds to a position in which the plate L has a vertical median plane substantially coinciding with the vertical median plane of the rollers 210 of the roller conveyor 21.

At the same time as the driving of the lever 41 or after the driving of the lever 41, the rotation of the roller 210 of the roller conveyor 21 may be stopped, and the motor 211 is stopped.

By thus firmly stopping the plate L and centering the plate L on the resting plane a, the printing machine 10 is configured to be able to drive the printing device 30 to decorate the surface L1 of the plate L according to a predetermined decoration.

Specifically, the printing device 30 is driven by the linear motor 37 to slide the supporting empty wagon 35 in the sliding direction D, for example, in the first sliding direction (see the supporting empty wagon at the end stop position in fig. 10 and 14).

Thus, by supporting the carriage 35, the set of print heads 31 is slid in such a sliding direction D, releasing the predetermined decoration onto the surface L1 of the board L.

For example, by means of a single outward stroke (or single pass) along the first sliding direction, the set of print heads 31 can deposit the entire decoration (and the entire surface L1 of the plaque L or in any case the entire area of the plaque L which contains the entire decoration constituting the decoration of the plaque L).

Alternatively or additionally, the set of printing heads 31 can deposit the entire decoration (and the entire surface L1 of the plaque L or in any case the entire area of the plaque L containing the entire decoration constituting the decoration of the plaque L) through a plurality of outward and/or return strokes (or a plurality of strokes) along the first sliding direction and along the opposite second sliding direction.

Since the locking and centring assembly 40 brings the plate L to a complete stop on the resting plane a defined by the roller conveyor 21, the printing device 30 deposits drops of decorative fluid with great precision in a position predetermined by the decorative pattern (and in a multi-pass manner).

To facilitate the deposition of decorative objects, the heating devices 38 (i.e., two heating devices 38) may be actuated to effectively preheat the surface L1 prior to depositing the decorative fluid and/or to dry the decorative fluid once it has been deposited on the preheated surface L1.

Once the deposition of decorations on the surface L1 of the sheet L has ended, i.e. at the end of one or more runs of the set of printing heads 31 on the surface L1, it is sufficient to bring the rods 41 back into their deployed position and the front bezel 43 back into its non-interfering position, and by rotating the rollers 210 of the roller conveyor 21, the sheet L thus released and decorated can be made to travel towards the next processing station of the system.

In the case where it is desired to use the printing machine 10 as a single-pass machine, it is sufficient to leave the locking and centring assembly 40 free, i.e. to leave the bars 41 in the deployed position and the front stop 43 in the non-interfering position, while the sheet L passes over the roller conveyor 21 in the direction of travel B, the printing device 30 fixed on the resting plane a releasing the decoration onto the (entire) surface L1 of the sheet L in a single pass.

The invention thus conceived is susceptible of numerous modifications and variations, all of which are covered by the inventive concept.

Moreover, protection of aspects associated with printing device 10 may be obtained independently of the locking and centering assembly 40 described above, and for example, printing device 10 can be used as a single pass machine or can be used in other modes of operation.

Moreover, all the details may be replaced with other technically equivalent elements.

The materials used, as well as the contingent shapes and dimensions, may be any according to requirements without thereby departing from the scope of protection of the claims.

Claims

1. An inkjet printer (10), the inkjet printer (10) for printing on a board (L), comprising:

a support (20) for supporting the plate (L);

a locking and centering assembly (40) configured to contact the plate (L) to temporarily lock and center the plate (L) on the support (20); and

a printing device (30) provided with at least one inkjet printing head (31), said at least one inkjet printing head (31) being movable in a sliding direction (D) with respect to said support (20) and being spaced apart from said support (20), wherein said inkjet printing head (31) is configured to release decorations on a surface (L1) of said board (L) resting on said support (20).

2. Inkjet printer (10) according to claim 1, characterized in that said support (20) comprises a horizontal resting plane (a) comprising a travel assembly for the travel of the supported plate (L) along a predetermined horizontal travel direction (B).

3. Inkjet printer (10) according to claim 2, characterized in that said travelling assembly comprises a motorized roller conveyor (21), wherein the rollers (210) of said roller conveyor (21) define integrally said rest plane (a).

4. Inkjet printer (10) according to claim 3, characterized in that the roller (210) is a ceramic roller.

5. Inkjet printer (10) according to claim 1, characterized in that said locking and centering assembly (40) comprises at least one pair of rods (41), said at least one pair of rods (41) being mutually movable on said support (20) and being configured to releasably laterally grip a plate (L) arranged to rest on said support (20).

6. Inkjet printer (10) according to claim 2, characterized in that said locking and centering assembly (40) comprises at least one front shutter (43), said at least one front shutter (43) being adapted to stop the travel of said plate (L) along said direction of travel (B).

7. Inkjet printer (10) according to claim 1, characterized in that said printing means (30) comprise a set of printing heads (31) placed side by side along a side by side direction (C), said set of printing heads (31) being offset and/or aligned along said side by side direction (C) and being mutually movable as a whole.

8. Inkjet printer (10) according to claim 7, characterized in that the dimension of said set of printing heads (31) in said side by side direction (C) is at least equal to or greater than the edge of said sheet L to be decorated.

9. Inkjet printer (10) according to claim 2, characterized in that the sliding direction (D) of the printing head (31) of the printing device (30) on the support (20) is horizontal and parallel to the travelling direction (B).

10. Inkjet printer (10) according to claim 2, characterized in that the sliding direction (D) of the printing head (31) of the printing device (30) on the support (20) is horizontal and perpendicular to the travelling direction (B).

11. Inkjet printer (10) according to claim 1, characterized in that the printing device (30) comprises a heating device (38), the heating device (38) being movable on the support (20) as a whole with the print head (31) along the sliding direction (D) and spaced apart from the support (20).

12. Inkjet printer (10) according to claim 11, characterized in that the heating device (38) is aligned with the print head in an alignment direction parallel to the sliding direction (D) and is arranged upstream or downstream of the print head (31) in the direction of sliding of the print head (31) in the sliding direction (B).

13. Inkjet printer (10) according to claim 11, characterized in that the heating means (38) comprise at least one infrared lamp.

14. Inkjet printer (10) according to claim 1, characterized in that the inkjet printer (10) comprises a measuring assembly (45), the measuring assembly (45) being configured to measure at least one dimension of the plate (L).

15. A method of inkjet printing on a board (L), comprising the steps of:

supporting the plate (L) on a support (20);

temporarily locking the plate (L) on the support (20) by bringing it into contact with a locking and centering assembly (40) movable on the support (20); and

-releasing a decoration on a surface (L1) of the plate (L) by moving an inkjet printing head (31) of a printing device with respect to the plate (L) resting on the support (20) and spaced apart from the support (20).